Final answer:
The options given represent different ways that imperialist nations historically exerted their influence. However, social dominance was not a primary method on its own but rather a result of the military, political, and economic domination. Thus, the correct answer to the question is (c) socially.
Step-by-step explanation:
The concept of Imperialism typically involved a stronger country exerting control over other weaker countries in a variety of ways. These methods included military dominance, establishing political control, exerting economic influence, and sometimes, imposing social and cultural norms. However, when it comes to the options presented in the question - militarily (a), politically (b), economically (d) are all methods by which imperialists nations have historically dominated other territories. Social dominance (c) was a byproduct of these other forms of domination and can be considered a part of Imperialism, but it's not typically listed as a separate primary method.
In the context of the question, European powers like Great Britain and France seeking territorial expansion through Imperialism primarily did so through military conquest, political control, and economic exploitation. They often just imposed their social and cultural values as part of these other forms of dominance, rather than pursuing social dominance as an independent aim. Thus, the answer to the question would be (c) socially, as it is the option that least aligns with the primary methods of Imperial dominion.